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<h1 style="margin-top:0px">Tutorial 03 - Using helper classes</h1>
<p>
<b>I</b>n this tutorial we will learn how to use some of <b>HGE</b> helper classes.
First, we include all the needed headers and declare the global pointer to
the <b>HGE</b> interface that is required by most of the helper classes to work:
</p>
<pre>
#include &lt;hge.h&gt;
#include &lt;hgesprite.h&gt;
#include &lt;hgefont.h&gt;
#include &lt;hgeparticle.h&gt;

HGE *hge=0;
</pre>
<p>
Now we declare the pointers to the <b>HGE</b> objects we will use.
</p>
<pre>
hgeSprite*          spr;
hgeSprite*          spt;
hgeFont*            fnt;
hgeParticleSystem*  par;

HTEXTURE            tex;
</pre>
<p>
In the <b>FrameFunc</b> (frame function) we update the particle system object:
we adjust it's emission rate based on the current sprite
speed and move it to the current sprite location.
</p>
<pre>
  par->info.nEmission=(int)(dx*dx+dy*dy)*2;
  par->MoveTo(x,y);
  par->Update(dt);
</pre>
<p>
In the <b>RenderFunc</b> we render all our objects, calling their render methods:
</p>
<pre>
  hge->Gfx_BeginScene();
  hge->Gfx_Clear(0);
  par->Render();
  spr->Render(x, y);
  fnt->printf(5, 5, HGETEXT_LEFT, "dt:%.3f\nFPS:%d",
              hge->Timer_GetDelta(), hge->Timer_GetFPS());
  hge->Gfx_EndScene();
</pre>
<p>
In the <b>WinMain</b> function after <b>HGE</b> is initiated we
create the <b>HGE</b> objects, that we will use. First, we create
and set up a sprite:
</p>
<pre>
    spr=new hgeSprite(tex, 96, 64, 32, 32);
    spr->SetColor(0xFFFFA000);
    spr->SetHotSpot(16, 16);
</pre>
<p>
Then we load a font. The font is represented with two disk files:
<b>font1.fnt</b> and <b>font1.png</b>.
</p>
<pre>
    fnt=new hgeFont("font1.fnt");
</pre>
<p>
We create a particle system and a sprite for it:
</p>
<pre>
    spt=new hgeSprite(tex, 32, 32, 32, 32);
    spt->SetBlendMode(
              BLEND_COLORMUL | BLEND_ALPHAADD | BLEND_NOZWRITE);
    spt->SetHotSpot(16, 16);
    par=new hgeParticleSystem("trail.psi", spt);
    par->Fire();
</pre>
<p>
Now all our objects have been created and we start the game loop:
</p>
<pre>
    hge->System_Start();
</pre>
<p>
When the game loop is finished, we delete all created <b>HGE</b> objects:
</p>
<pre>
    delete par;
    delete fnt;
    delete spt;
    delete spr;
</pre>
<p>
The rest of shutdown process is identical to the one demonstrated in previous tutorials.
<br><br>
The complete source code with detailed comments for this tutorial you may find in the folder
<b>tutorials\tutorial03</b>. The required media files you'll find in the folder <b>tutorials\precompiled</b>.
</p>
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